Your ACoS targets will decide how our algorithm suggests bid changes. Decide what your goals are for each campaign; some examples are increased efficiency, increased sales, or more impressions. Then define what the ACoS target is for those goals. For efficiency goals, we suggest keeping your ACoS targets conservative, no more than 10% lower than the current ACoS of that campaign.
https://prestozon.com/2017/10/06/setting-acos-targets/